Transportable Energy Storage Devices

ABSTRACT

Aspects of the disclosure can relate to transportable energy storage devices for furnishing power to down-hole electrical devices of a drill string. In embodiments, a system for furnishing electrical power includes a vessel that can be transported through a drill pipe (e.g., from the surface) towards a down-hole tool coupled to an end of the drill pipe. An energy storage device can be disposed within or defined by the vessel. The energy storage device can have an output terminal that can be operably coupled with an input terminal of the down-hole tool or operably coupled with an input terminal of a second energy storage device that directly or indirectly furnishes power to the down-hole tool.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a non-provisional patent application of co-pending U.S. provisional patent application Ser. No. 62/057,932, filed on Sep. 30, 2014, and entitled “Energy Storage Devices and Energy Storage Device Inductive Connections,” which is hereby incorporated in its entirety for all intents and purposes by this reference.

BACKGROUND

Oil wells are created by drilling a hole into the earth using a drilling rig that rotates a drill string (e.g., drill pipe) having a drill bit attached thereto. The drill bit, aided by the weight of pipes (e.g., drill collars) cuts into rock within the earth. Drilling fluid (e.g., mud) is pumped into the drill pipe and exits at the drill bit. The drilling fluid may be used to cool the bit, lift rock cuttings to the surface, at least partially prevent destabilization of the rock in the wellbore, and/or at least partially overcome the pressure of fluids inside the rock so that the fluids do not enter the wellbore. Other equipment can also be used for evaluating formations, fluids, production, other operations, and so forth.

Downhole equipment can be powered by remote energy sources that power the equipment via transmission lines (e.g., electrical, optical, mechanical, or hydraulic transmission lines). Downhole equipment can also be powered by local energy sources such as local generators (e.g., mud turbines) or energy storage devices (e.g., battery packs) coupled with the equipment.

SUMMARY

Aspects of the disclosure can relate to transportable energy storage devices for furnishing power to down-hole electrical devices of a drill string. In embodiments, a system for furnishing electrical power includes a vessel that can be transported through a drill pipe (e.g., from the surface) towards a down-hole tool coupled to an end of the drill pipe. An energy storage device can be disposed within or defined by the vessel. The energy storage device can have an output terminal that can be operably coupled with an input terminal of the down-hole tool or operably coupled with an input terminal of a second energy storage device that directly or indirectly furnishes power to the down-hole tool. In an example implementation, the energy storage device can be transported through a drill string pipe from the surface to directly power a down-hole tool or to charge or supplement another down-hole energy storage device that was previously lowered within a borehole.

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

FIGURES

Embodiments of transportable energy storage devices and inductive connection circuits are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components.

FIG. 1 illustrates an example system in which embodiments of a transportable energy storage device can be implemented.

FIG. 2 illustrates an example system in which embodiments of a transportable energy storage device can be implemented.

FIG. 3 illustrates an embodiment of a transportable energy storage device.

FIG. 4 illustrates an end view of two inductive coils in accordance with an example system in which embodiments of a transportable energy storage device can be implemented.

FIG. 5 illustrates an embodiment of a transportable energy storage device.

FIG. 6 illustrates an inductive connection circuit that can be implemented in a system in which embodiments of a transportable energy storage device can be implemented, such as the system illustrated in FIGS. 1 and 2.

FIG. 7 illustrates an inductive connection circuit that can be implemented in a system in which embodiments of a transportable energy storage device can be implemented, such as the system illustrated in FIGS. 1 and 2.

FIG. 8A illustrates inductive connectors that can be implemented in a system in which embodiments of a transportable energy storage device can be implemented, such as the system illustrated in FIGS. 1 and 2.

FIG. 8B illustrates inductive connectors that can be implemented in a system in which embodiments of a transportable energy storage device can be implemented, such as the system illustrated in FIGS. 1 and 2.

FIG. 9 illustrates an inductive connection circuit that can be implemented in a system in which embodiments of a transportable energy storage device can be implemented, such as the system illustrated in FIGS. 1 and 2.

FIG. 10 illustrates an embodiment of a transportable energy storage device.

DETAILED DESCRIPTION

FIG. 1 depicts a wellsite system 100 in accordance with one or more embodiments of the present disclosure. The wellsite can be onshore or offshore. A borehole 102 is formed in subsurface formations by directional drilling. A drill string 104 extends from a drill rig 106 and is suspended within the borehole 102. In some embodiments, the wellsite system 100 implements directional drilling using a rotary steerable system (RSS). For instance, the drill string 104 is rotated from the surface, and down-hole devices move the end of the drill string 104 in a desired direction. The drill rig 106 includes a platform and derrick assembly positioned over the borehole 102. In some embodiments, the drill rig 106 includes a rotary table 108, kelly 110, hook 112, rotary swivel 114, and so forth. For example, the drill string 104 is rotated by the rotary table 108, which engages the kelly 110 at the upper end of the drill string 104. The drill string 104 is suspended from the hook 112 using the rotary swivel 114, which permits rotation of the drill string 104 relative to the hook 112. However, this configuration is provided by way of example and is not meant to limit the present disclosure. For instance, in other embodiments a top drive system is used.

A bottom hole assembly (BHA) 116 is suspended at the end of the drill string 104. The bottom hole assembly 116 includes a drill bit 118 at its lower end. In embodiments of the disclosure, the drill string 104 includes a number of drill pipes 120 that extend the bottom hole assembly 116 and the drill bit 118 into subterranean formations. Drilling fluid (e.g., mud) 122 is stored in a tank and/or a pit 124 formed at the wellsite. The drilling fluid can be water-based, oil-based, and so on. A pump 126 displaces the drilling fluid 122 to an interior passage of the drill string 104 via, for example, a port in the rotary swivel 114, causing the drilling fluid 122 to flow downwardly through the drill string 104 as indicated by directional arrow 128. The drilling fluid 122 exits the drill string 104 via ports (e.g., courses, nozzles) in the drill bit 118, and then circulates upwardly through the annulus region between the outside of the drill string 104 and the wall of the borehole 102, as indicated by directional arrows 130. In this manner, the drilling fluid 122 cools and lubricates the drill bit 118 and carries drill cuttings generated by the drill bit 118 up to the surface (e.g., as the drilling fluid 122 is returned to the pit 124 for recirculation).

In some embodiments, the bottom hole assembly 116 includes down tools, such as a logging-while-drilling (LWD) module 132, a measuring-while-drilling (MWD) module 134, a rotary steerable system 136, a motor, and so forth (e.g., in addition to the drill bit 118). The logging-while-drilling module 132 can be housed in a drill collar and can contain one or a number of logging tools. It should also be noted that more than one LWD module and/or MWD module can be employed (e.g. as represented by another logging-while-drilling module 138). In embodiments of the disclosure, the logging-while drilling modules 132 and/or 138 include capabilities for measuring, processing, and storing information, as well as for communicating with surface equipment, and so forth.

The measuring-while-drilling module 134 can also be housed in a drill collar, and can contain one or more devices for measuring characteristics of the drill string 104 and drill bit 118. The measuring-while-drilling module 134 can also include components for generating electrical power for down-hole tools (e.g., sensors, electrical motors, transmitters, receivers, controllers, energy storage devices, and so forth). For example, the system can include a mud turbine generator (also referred to as a “mud motor”) powered by the flow of the drilling fluid 122. However, this configuration is provided by way of example and is not meant to limit the present disclosure. In other embodiments, other power and/or battery systems can be employed. The measuring-while-drilling module 134 can include one or more of the following measuring devices: a weight-on-bit measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a stick slip measuring device, a direction measuring device, an inclination measuring device, and so on.

In embodiments of the disclosure, the wellsite system 100 is used with controlled steering or directional drilling. For example, the rotary steerable system 136 is used for directional drilling. As used herein, the term “directional drilling” describes intentional deviation of the wellbore from the path it would naturally take. Thus, directional drilling refers to steering the drill string 104 so that it travels in a desired direction. In some embodiments, directional drilling is used for offshore drilling (e.g., where multiple wells are drilled from a single platform). In other embodiments, directional drilling enables horizontal drilling through a reservoir, which enables a longer length of the wellbore to traverse the reservoir, increasing the production rate from the well. Further, directional drilling may be used in vertical drilling operations. For example, the drill bit 118 may veer off of a planned drilling trajectory because of the unpredictable nature of the formations being penetrated or the varying forces that the drill bit 118 experiences. When such deviation occurs, the wellsite system 100 may be used to guide the drill bit 118 back on course.

Drill assemblies can be used with, for example, a wellsite system (e.g., the wellsite system 100 described with reference to FIG. 1). For instance, a drill assembly can comprise a bottom hole assembly suspended at the end of a drill string (e.g., in the manner of the bottom hole assembly 116 suspended from the drill string 104 depicted in FIG. 1). In some embodiments, a drill assembly is implemented using a drill bit. However, this configuration is provided by way of example and is not meant to limit the present disclosure. In other embodiments, different working implement configurations are used. Further, use of drill assemblies in accordance with the present disclosure is not limited to wellsite systems described herein. Drill assemblies can be used in other various cutting and/or crushing applications, including earth boring applications employing rock scraping, crushing, cutting, and so forth.

A drill assembly includes a body for receiving a flow of drilling fluid. The body comprises one or more crushing and/or cutting implements, such as conical cutters and/or bit cones having spiked teeth (e.g., in the manner of a roller-cone bit). In this configuration, as the drill string is rotated, the bit cones roll along the bottom of the borehole in a circular motion. As they roll, new teeth come in contact with the bottom of the borehole, crushing the rock immediately below and around the bit tooth. As the cone continues to roll, the tooth then lifts off the bottom of the hole and a high-velocity drilling fluid jet strikes the crushed rock chips to remove them from the bottom of the borehole and up the annulus. As this occurs, another tooth makes contact with the bottom of the borehole and creates new rock chips. In this manner, the process of chipping the rock and removing the small rock chips with the fluid jets is continuous. The teeth intermesh on the cones, which helps clean the cones and enables larger teeth to be used. A drill assembly comprising a conical cutter can be implemented as a steel milled-tooth bit, a carbide insert bit, and so forth. However, roller-cone bits are provided by way of example and are not meant to limit the present disclosure. In other embodiments, a drill assembly is arranged differently. For example, the body of the bit comprises one or more polycrystalline diamond compact (PDC) cutters that shear rock with a continuous scraping motion.

In embodiments of the disclosure, the body of a drill assembly can define one or more nozzles that allow the drilling fluid to exit the body (e.g., proximate to the crushing and/or cutting implements). The nozzles allow drilling fluid pumped through, for example, a drill string to exit the body. For example, drilling fluid can be furnished to an interior passage of the drill string by the pump and flow downwardly through the drill string to a drill bit of the bottom hole assembly, which can be implemented using, for example, a drill assembly. Drilling fluid then exits the drill string via nozzles in the drill bit, and circulates upwardly through the annulus region between the outside of the drill string and the wall of the borehole. In this manner, rock cuttings can be lifted to the surface, destabilization of rock in the wellbore can be at least partially prevented, the pressure of fluids inside the rock can be at least partially overcome so that the fluids do not enter the wellbore, and so forth.

Modern oil and gas exploration increasingly uses electronic devices in the borehole to provide measurements, and for control and operational optimization. When operating electronics as part of a drill string, other down-hole equipment/tools and/or strings (e.g., for well testing, well simulation, well monitoring, formation evaluation, and so forth), available power in the borehole may be limited near a bottom hole assembly 116. In some cases, electrical power can be generated by turbines while fluids are pumped into and/or out of a well, but this technique may not be efficient when there is little or no movement of fluids. Batteries can also be installed in electronic equipment to provide electrical power in a borehole, but batteries have a finite energy storage capacity, which limits the amount of time the equipment can be operated. In some cases, larger batteries may be used, but the amount of space available in the borehole is also finite, limiting the size of such batteries. In other cases, higher power density batteries may be used, but such batteries may be more prone to failure (e.g., in the high temperature operating conditions present down-hole). Another, factor that can limit the autonomy of battery powered systems is the effect of self-discharge. As used herein, the term “self-discharge” describes energy that is wasted in a battery (e.g., not provided to a device powered by the battery). Generally, self-discharge of a battery increases with temperature, and, in some cases, may increase exponentially with temperature. Thus, batteries deployed in oil wells and/or gas wells may be strongly affected by self-discharge (e.g., due to the time such batteries spend at high temperatures).

Systems and apparatuses are described herein that can be used to connect one or more separate batteries and/or other energy storage devices to a down-hole tool (e.g., (e.g., LWD, MWD, various sensors, electrical motors, transmitters, receivers, controllers, other energy storage devices, and so forth). Further, such energy storage devices can be deployed on an as-needed basis. In this manner, the devices can be stored in more favorable conditions (e.g., at the surface of a wellsite instead of down-hole during tripping, normal operations, and so forth). Then, when an energy storage device is needed, it can be supplied (e.g., pumped, dropped, slid or otherwise actuated) towards a down-hole tool to be powered by the energy storage device (e.g., dropped, slid or pumped down the pipe string until it connects with a down-hole tool to be powered or another energy storage device to by charged or supplemented). As described herein, when the energy storage device comprises a battery, the battery can be stored at lower temperatures for a longer time, reducing and/or minimizing the effect of self-discharge. In this manner, the energy storage device can have a smaller energy storage capacity (e.g., since more energy will be available when needed), which can correspond to a smaller overall size. Further, because the energy storage device can be deployed when needed, cost savings can be achieved (e.g., by reducing or eliminating the need for backup batteries, which may not actually be needed), reliance on partially-spent batteries can be reduced, the costs of battery disposal can be reduced, and so forth.

As shown in FIGS. 1 and 2, an energy storage device (e.g., battery or battery pack) can be contained within or defined by a transportable vessel 200 that is to be fed into a drill string pipe 120 or similar structure (e.g., tubular passage or conduit such as a testing string pipe, a completion pipe, a stimulation string, a formation evaluation string, a monitoring string, or the like). It is noted that the passage way need not have a circular or elliptical cross section. For example, the vessel 200 can be structured for transportation through a passage way having a rectangular cross section or any other shape. In embodiments of the disclosure (e.g., as shown in FIGS. 2 through 5), the vessel 200 has a body (e.g., an annular body) defining a longitudinal passage 206 therethrough. In other embodiments, the vessel 200 can have a substantially cylindrical body (e.g., as shown in FIG. 10, wherein vessel 400 has a cylindrical body structure 402). In embodiments, the vessel 200 can have an energy storage device disposed in the body. For example, the one or more battery cells can be disposed within or defined by a wall of the annular body (e.g., a primary battery and possibly one or more secondary batteries). Thus, in some embodiments, the energy storage device is configured as a battery pack. In some embodiments, the vessel 200 can be pumped into an oil well and/or a gas well to provide energy to power a tool in the wellbore. That is, the vessel 200 can be actuated towards a deployment site (e.g., for connection with a down-hole tool or another energy storage device) by fluid flow. The vessel 200 can also be actuated by gravitational force (e.g., free fall) towards the deployment site.

The energy storage device includes an output terminal 202 (e.g., a connector such as an electrical contact, an inductive connection coil, or the like) for operably coupling the energy storage device to a powered device, where connection between the energy storage device and the powered device can be made while the powered device is deployed (e.g., in the well) by transporting the vessel 200 housing the energy storage device through the pipe to the powered device. The powered device can be a down-hole tool having an input terminal 140 for connecting with output terminal 202, or the powered device can be a second energy storage device (e.g., a previously deployed battery) that is to be charged or supplemented by the energy storage device that is transported by vessel 200. In some embodiments, the output terminal 202 can establish an inductive connection between the energy storage device and a downhole tool and/or another energy storage device (e.g., as more described in more detail with reference to FIGS. 6 through 9 below). However, inductive coupling is provided by way of example and is not meant to limit the present disclosure. In other embodiments, the connector can be an exposed electrical contact. In further embodiments, the connector can be an electrical contact that can be covered by a biased cover (e.g., a spring-loaded sleeve), where the electrical contact is exposed when the energy storage device contacts a tool and/or another energy storage device.

In embodiments of the disclosure, the output terminal 202 facilitates energy transfer between the energy storage device and the powered device. Further, in some embodiments, the energy storage device includes input terminal 204 for connecting the energy storage device to an additional energy storage device (e.g., that can also be transported by additional vessels 200). For example, a second energy storage device can be used to charge (e.g., recharge) the first energy storage device, furnish energy to a powered device along with the first energy storage device (e.g., in series with the first energy storage device, in parallel with the first energy storage device, and so on), and/or directly furnish energy to the powered device (e.g., bypassing the first energy storage device). The additional energy storage device itself includes an output terminal 202, and may also include an input terminal 204 for connecting the second energy storage device to a third energy storage device, and so on. In this manner, energy storage devices can be transported via respective vessels 200 and linked together to provide additional energy (e.g., on an as-needed basis). These energy packs can also be furnished (e.g., pumped or dropped) into an oil well and/or a gas well to provide energy to other energy storage devices, electrically powered down-hole tools in the wellbore, and so forth.

Referring now to FIG. 3, an energy storage device is described in an example embodiment. The energy storage device can be contained within or defined by a vessel 200 having an annular configuration with a central passage 206 that fluid (e.g., mud) can move through. As shown, the energy storage device has an input terminal 204 at one or more of an end, a side, an internal wall, an external wall, and so on. The energy storage device can also have an output terminal 202, allowing other energy storage devices to attach or connect to the energy storage device. In this manner, an energy storage device can connect to another energy storage device, a tool, and so forth. However, a two-terminal energy storage device is provided by way of example and is not meant to limit the present disclosure. In other embodiments, the energy storage device can have more than two connectors (e.g., three connectors, four connectors, and so forth).

In some embodiments, the output terminal 202 of the energy storage device includes a conductive coil that can surround or be surrounded by a conductive coil of an input terminal terminal 204 or another energy storage device or by a conductive coil of an input terminal 140 of a downhole tool. For example, FIG. 4 shows an arrangement where the output terminal 202 of a first energy storage device is surrounded by the input terminal 204 of a second energy storage device when the first and second energy storage device are operably coupled with one another (e.g., forming an inductive connection between the two devices).

Referring to FIG. 5, shaping (e.g., rounding and/or chamfering) of edges 208 of the vessel 200 can be used to facilitate the connection between the energy storage device and other energy storage devices and/or tools, and/or to facilitate transportation and/or latching of the energy storage device. It should be noted that connections formed at the output terminal 202 or the input terminal 204 may have various forms and/or shapes. Further, other mechanical devices can be used to facilitate latching and/or connection between devices. In some embodiments, the energy storage device and/or a tool can include one or more biasing and/or damping mechanisms (e.g., a spring and/or a flexible gasket for damping the impact of the energy storage device on the tool and/or on another energy storage device). Magnetic connections can also be used to assist in aligning and/or fixing connections between the energy storage device and the powered device/tool.

Referring now to FIG. 2, pumping of the energy storage device contained or defined by the vessel 200 into a wellbore 120 is described. In this example, the wellbore 120 can represent a drill pipe, a completion string, a testing string, an open hole, and so forth. The vessel 200 can be placed into the wellbore 120, and one or more pumps can be used to create a pressure difference between the pressure above the vessel 200 and the pressure below the vessel 200 (e.g., such that the pressure above the vessel 200 is greater than the pressure below the vessel 200). The pressure difference can be used to transport (e.g., propel) the energy storage device down-hole towards a tool, another powered device, another energy storage pack, and so on. However, pumping is provided by way of example and is not meant to limit the present disclosure. In other embodiments, a pressure differential is not necessarily used to transport the energy storage device down-hole. For example, the energy storage device can be “dropped,” where gravity is used to transport the energy storage device to its intended location down-hole. Additional vessel structures can be employed to facilitate transport, such as vessel 400 shown in FIG. 10 which is described in further detail below.

Referring generally to FIGS. 6 through 9, circuitry for establishing inductive connections between an energy storage device a tool, a down-hole sub, and/or another energy storage are described. An inductive connection circuit 300 can include an energy storage device 301 (e.g., an energy storage device as described with reference to FIGS. 1 through 5 or FIG. 10). The energy storage device 301 can be pumped into an oil well and/or a gas well to provide energy to power a tool in the wellbore. The energy storage device 301 includes a primary inductor 305. A powered device 302 (e.g., a down-hole tool or another energy storage device) can include a secondary inductor 306 for connecting the energy storage device 301 to the powered device 302 when an inductive connection is established between the primary inductor 305 and the secondary inductor 306. Once the inductive connection is established, energy can be transferred between the energy storage device 301 and the powered device 302. For example, the energy storage device and/or additional energy storage devices can be used to power a down-hole tool.

In some embodiments, the energy storage device 301 is chargeable (e.g., rechargeable) by the tool when the inductive connection is established between the primary inductor 305 and the secondary inductor 306. Further, in some embodiments, the energy storage device 301 also includes a secondary inductor for receiving energy from another energy storage device, where the additional energy storage device also includes a primary inductor for connecting the second energy storage device to the first energy storage device 301 (e.g., when an inductive connection is established between the primary inductor of the second energy storage device and the secondary inductor of the first energy storage device). In this manner, energy can be transferred between the second energy storage device and the first energy storage device 301 and/or the powered device 302.

In some embodiments, the tool comprises a bottom hole assembly tool (e.g., a drill bit, a sensor, a measuring device, a rotary steerable system, a motor, etc.) suspended from a drill string. For example, the tool includes electronic equipment configured to measure and/or control the rate and/or direction of the drill string, such as sensors to sense formation types, sensors to prevent kick (out of control behavior), and so forth. However, a bottom hole assembly tool is provided by way of example and is not meant to limit the present disclosure. For example, in other embodiments, the tool can comprise a sub suspended from a drill string. The system also includes a pipe supporting the tool. The pipe is configured to transport fluid. For example, the pipe can be a drill pipe, a testing string pipe, a completion pipe, and so forth. As previously described, the pipe is also configured to transport the energy storage device to the tool.

Referring now to FIG. 6, the inductive connection circuit 300 is described in an example embodiment. In this example, the circuit 300 includes an energy storage device 301, a powered device 302, energy cells 303, an alternator 304, a primary inductor 305, a secondary inductor 306, a rectifier 307, and a tool electrical/electronic system 308. In some embodiments, the energy storage device 301 comprises an energy pack or cell implemented as a battery pack or battery cell, in which a battery provides a direct current (DC). In other embodiments, a rectifier, capacitor, or the like can be used to supply direct current. To supply an induction connector with alternating current (AC) (e.g., to induce current through an inductor on the other side of the connector), an alternator (e.g., configured as a DC/AC converter) can be used. The current induction can function in a similar manner as in an electrical transformer, transferring energy from one inductor to another.

In some embodiments, energy to the down-hole tool is supplied in a DC format to power electronics. In such cases, a rectifier (e.g., an AC/DC converter) can be used on the tool side of the connector. To avoid unnecessary discharge of the battery during transportation and/or storage, a switch 310 can be used to keep the battery or energy source disconnected from the rest of the system when it is not in use. In some embodiments, an activation solenoid 319 can be used to activate switches 310 and/or 311 (e.g., as illustrated in FIG. 7). In this example, the same inductive connector 305 can be used to activate such a switch. In some embodiments, a bi-stable switch can be used. A switch activation sub 312 may be used to activate the switch before use.

The two inductors 305 and 306 can be relatively close to one another to facilitate energy transfer. As shown in FIGS. 8A and 8B, respectively, the energy storage device 301 can be connected and disconnected from the powered device 302 (e.g., a down-hole tool or second energy storage device). In this example, the energy storage device 301 has an annular configuration, allowing fluid movement through the middle of the device 301. In some embodiments, the distance between the two inductors can be reduced (e.g., minimized) by inserting one electrical coil into the other during the connection operation (e.g., as discussed above with reference to FIG. 4).

In some embodiments, a second energy storage device can be used to charge (e.g., recharge) the first energy storage device 301, furnish energy to the powered device 302 along with the first energy storage device 301 (e.g., in series with the first energy storage device 301, in parallel with the first energy storage device 301, and so on), and/or directly furnish energy to the powered device 302 (e.g., bypassing the first energy storage device 301). For example, with reference to FIG. 9, an upper inductor 311 can be used to receive the power of another energy storage device to activate a stacking solenoid 315 that disconnects the energy of the energy storage device 301 and transmits the energy from the other energy storage device (stacking battery cell or pack) to the lower inductor 314.

FIG. 10 illustrates another embodiment of a transportable energy storage device that can be dropped, pumped or otherwise actuated from the surface, directly to the downhole BHA 116 or another deployment site of the drill string 104, travelling inside the drill pipes 120, to bring additional or emergency power supply to down-hole tools, without needing to pull out of the hole. One or more energy storage devices 401 (e.g., battery cells or packs) can be implemented in a vessel 400, such as a rocket or torpedo shaped vessel or any other container suitable for transporting the energy storage devices 401 to a deployment site (e.g., to a down-hole tool or to link up with another energy storage device that is coupled to a down-hole tool). In some embodiments, the energy storage devices 401 include LTC cells. However, Li-Polymer cells and other battery chemistries or capacitors can also be used. The vessel 400 can be designed to isolate the energy storage devices 401 contained therein from pressure. Internal packaging can also provide a good shock and vibrations absorption, by the mean of dampers, spacers, spring, potting, or the like.

The vessel 400 can be transported through the drill pipe 120 or a similar structure as described above. In embodiments, one or several energy storage devices 401 can be securely enclosed in a body 402 (e.g., pressure housing). An output terminal 403 (e.g., electrical contact or inductive connector) can be installed at an end of the vessel 403. This output terminal 403 can be structured to cooperatively couple (e.g., male-to-female or female-to-male) with an input terminal 404 of a down-hole tool (e.g., a BHA Power Management Sub Connector) or another energy storage device. In some embodiments, the coupling provides for a mechanical connection between the vessel 400 and BHA 116 or other deployment site, in addition to operably coupling the energy storage device 401 contained in the vessel 400 with the input terminal 404 of the powered device (e.g., tool or another energy device).

To control the vessel motion inside through the drill pipe 120, one or more centralizers 405 can be attached around the body 402 of the vessel 400 to help the vessel 400 slide inside the pipe 120 while keeping alignment with a central axis or other longitudinal axis of the pipe 120. The centralizers 405 can reduce friction between vessel 400 and pipe 120 in addition to aligning the vessel 400 with the powered device (e.g., aligning output terminal 403 with input terminal 404). In embodiments, the centralizers 405 can simply include low-friction material pads or housing mounted outside of the vessel body 402. In some embodiments, the centralizers 405 can include any other type of linear guiding element such as rollers, bearings, wheels, or the like. As shown in FIG. 10, the centralizers 405 can include protruding arms with rollers located at the ends of the arms.

A braking structure 406 can also be installed to control the speed of the vessel 400 as it is transported (e.g., free falls) through the pipe 120. The braking structure 406 can include an adjustable surface area plate that can be pre-set at the surface, taking into consideration mud parameter, deviation, depth, and so forth. The plate can operate to set a mud flow limit, thus a vessel speed limit. The braking structure 406 can include openings or spaced apart elements such that a mud path is still possible once the vessel 400 is fixed at the deployment site (e.g., coupled with the powered device). The braking structure 406 can also be used to push the vessel 400 inside the pipe 120 (e.g., in case the vessel 400 is stuck), acting as a piston when the mud flow is turned on. As mentioned above, an input terminal (e.g., like terminal 404) can also be installed at the rear of the vessel 400 to allow several vessels 400 containing energy storage devices 401 to be stacked on each other.

In some embodiments, output terminal 403 and input terminal 404 can implement a self-locking connection. For example, a mechanical guiding system (i.e. similar to airplane boom drogue adapter) can be implemented to ensure a proper connection, accounting for possible misalignment, angular shift, and so forth. The input terminal 404 of the powered device can be protected from mud flow by a selective cover (e.g., spring-loaded flap or the like) that can be opened by a structural element of the output terminal 403 but not by pressure from mud flow, rock cuttings, etc. Dampeners (e.g., elastomers) can be added to connector parts to facilitate a smooth connection when the vessel 400 approaches at a potentially high speed.

During a connection, the vessel 400 is inserted inside the drill pipes inner diameter at the surface. The vessel 400 is dropped inside the well, sliding inside the drill pipe 120. In some implementations, fluid (e.g., mud) flow is also used to propel the vessel 400. At the end of the drill pipes string, the BHA 116 or a tool is fixed. At the top of the BHA 116 or tool, a power management sub can be mounted. Due to gravity, and/or mud flow inside the drill pipes 120, the vessel 400 slides until reaching the power management sub. At a front end of the vessel 400, a guiding and connection system can physically and operably couple to an input terminal 404 (e.g., socket) of the power management sub, tool, second energy storage device, or any other powered device. This can create a strong mechanical and electrical connection between the vessel 400 and the powered device, and the energy storage device is therefore enabled to furnish an electrical current. In some implementations, an input terminal is positioned at a rear end of the vessel 400. The input terminal (e.g., a socket) can be structured to tightly connect with the output terminal 403 so that several vessels 400 can be dropped from the surface and stacked on each other to transport and link multiple energy storage devices 401 (e.g., either to supply energy in series, parallel, and/or on an as-needed basis).

In some embodiments, vessels 400 carrying energy storage devices 401 can also be used to convey a signal from the surface. When the vessel 400 connects to a tool, for example, the voltage at the output terminal 403 can be interpreted by the tool as an instruction (e.g., to open a valve, fire a gun, shutdown, etc.). In some embodiments, the vessel 400 can also include a memory device (e.g., flash memory, solid-state disk (SSD), etc.) that contains an instruction sequence. When the vessel 400 connects to the tool, the data stored by the memory device can be accessed by the tool.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from electrical power generation systems. Features shown in individual embodiments referred to above may be used together in combinations other than those which have been shown and described specifically. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. 

What is claimed is:
 1. A system for furnishing electrical power to down-hole electrically powered devices of a drill string, comprising: a vessel transportable through a drill pipe towards a down-hole tool of the drill pipe; an energy storage device disposed within or defined by the vessel, the energy storage device including an output terminal configured to be operably coupled with an input terminal of the down-hole tool or an input terminal of a second energy storage device.
 2. The system as recited in claim 1, wherein the output terminal is configured to be inductively coupled with the input terminal of the down-hole tool or the input terminal of the second energy storage device.
 3. The system as recited in claim 2, wherein the output terminal of the energy storage device comprises a first conductive coil, wherein the first conductive coil is configured to at least partially surround or be surrounded by a second conductive coil.
 4. The system as recited in claim 1, wherein the output terminal is configured to be directly coupled with the input terminal of the down-hole tool or the input terminal of the second energy storage device.
 5. The system as recited in claim 1, wherein the vessel comprises an annular body allowing fluid flow through an inner cavity of the annular body.
 6. The system as recited in claim 1, wherein the vessel comprises a substantially cylindrical body.
 7. The system as recited in claim 6, wherein the vessel includes a centralizer at least partially surrounding the substantially cylindrical body, the centralizer being structured to align the substantially cylindrical body with the down-hole tool or the second energy storage device.
 8. The system as recited in claim 7, wherein the centralizer includes one or more wheels or bearings to reduce friction between the vessel and an inner surface of the pipe while the vessel is transported therethrough.
 9. The system as recited in claim 1, wherein the vessel is transportable by at least one of gravitational force or flow of drilling fluid.
 10. A system for furnishing electrical power to electrically powered devices, comprising: a vessel transportable through a passage towards an electrically powered device located at an end of the passage; an energy storage device disposed within or defined by the vessel, the energy storage device including an output terminal configured to be operably coupled with an input terminal of the electrically powered device or an input terminal of a second energy storage device.
 11. The system as recited in claim 10, wherein the output terminal is configured to be inductively coupled with the input terminal of the electrically powered device or the input terminal of the second energy storage device.
 12. The system as recited in claim 11, wherein the output terminal of the energy storage device comprises a first conductive coil, wherein the first conductive coil is configured to at least partially surround or be surrounded by a second conductive coil.
 13. The system as recited in claim 10, wherein the output terminal is configured to be directly coupled with the input terminal of the electrically powered device or the input terminal of the second energy storage device.
 14. The system as recited in claim 10, wherein the vessel comprises an annular body allowing fluid flow through an inner cavity of the annular body.
 15. The system as recited in claim 10, wherein the vessel comprises a substantially cylindrical body.
 16. The system as recited in claim 15, wherein the vessel includes a centralizer at least partially surrounding the substantially cylindrical body, the centralizer being structured to align the substantially cylindrical body with the electrically powered device or the second energy storage device.
 17. The system as recited in claim 16, wherein the centralizer includes one or more wheels or bearings to reduce friction between the vessel and an inner surface of the pipe while the vessel is transported therethrough.
 18. An apparatus for furnishing energy to electrically powered devices, comprising: a transportable vessel having a substantially cylindrical body configured to transport through a tubular passage; a centralizer at least partially surrounding the substantially cylindrical body, the centralizer being structured to maintain the substantially cylindrical body aligned with a longitudinal axis of the tubular passage; an energy storage device disposed within or defined by the vessel; and an output connector coupled to the energy storage device, the output connector being located at an end of the substantially cylindrical body and being configured to at least partially fit within an input socket of an electrically powered device or a second energy storage device.
 19. The apparatus as recited in claim 18, wherein the centralizer includes openings or spaced apart elements that allow fluid to flow around the substantially cylindrical body.
 20. The apparatus as recited in claim 18, wherein the tubular passage comprises at least one of: a drill pipe, a testing string pipe, a completion pipe, a stimulation string, a formation evaluation string, or a monitoring string. 